The American Society for Testing and Materials (ASTM D288 standard definition of the terms relating to petroleum) defines a lubricating grease as a solid to semi-fluid product of dispersion comprising a thickening agent and a liquid lubricant. Other ingredients imparting special properties may be included. This definition indicates that a grease is a liquid lubricant thickened in order to provide properties that are not provided solely by the liquid lubricant. Typically, greases are employed in dynamic rather than static applications. Gels are normally classified as a colloid and provide utility in non-dynamic applications ranging from sol-gels to cosmetic applications.
Conventional grease formulations are described in "Synthetic Lubricants and High-Performance Functional Fluids", edited by Ronald L. Shubkin (dated 1993). The characteristics of soap based greases, additives and methods for making conventional greases are described in "The Chemistry of Soap Base Greases" by Glen Brunette, "Additives For Grease", by Dr. Miles Hutchings and "Grease Manufacture in Conventional Kettles" by K. F. Montgomery all of which were presented at the 63rd NLGI Annual Meeting, October 1996. The disclosure of the previously identified publications is hereby incorporated by reference.
Commercial industrial practice employs lubricating films and greases to prevent galling and fretting. The increased efficiency and complexity of modern machines often require such films and greases to perform under severe operating and environmental conditions. While the composition of a gel may be similar to a grease, typically gels are employed to solve non-lubricating problems. There is a need in this art for lubricants, greases and gels that also impart corrosion resistance.